I carry a light pretty much all the time, either a standard Zippo or a Zippo upgraded with a Z-Plus butane insert. I also have a Country Comm Stainless Pea Lighter on my key-chain.

If I had to pick just one fire starter to carry with me in the field it would be a Spark-Lite kit, specifically one of the metal ones. So far, Spark-Lites have been 100% reliable for me in all conditions I have used one.